cp -i: adjust the behavior to match the GNU change

Just like mv

Note that cp -i -u won't show the overwrite question

Matches the change upstream
7a69df88999bedd8e9fccf9f3dfa9ac6907fab66

src/uu/cp/src/cp.rs

@@ -78,6 +78,7 @@ quick_error! {
         StripPrefixError(err: StripPrefixError) { from() }
 
         /// Result of a skipped file
+        /// Currently happens when "no" is selected in interactive mode
         Skipped { }
 
         /// Result of a skipped file
@@ -1018,7 +1019,11 @@ fn show_error_if_needed(error: &Error) -> bool {
         // When using --no-clobber, we don't want to show
         // an error message
         Error::NotAllFilesCopied => (),
-        Error::Skipped => (),
+        Error::Skipped => {
+            // touch a b && echo "n"|cp -i a b && echo $?
+            // should return an error from GNU 9.2
+            return true;
+        }
         _ => {
             show_error!("{}", error);
             return true;

tests/by-util/test_cp.rs

@@ -234,6 +234,16 @@ fn test_cp_arg_update_interactive() {
         .no_stderr();
 }
 
+#[test]
+fn test_cp_arg_update_interactive_error() {
+    new_ucmd!()
+        .arg(TEST_HELLO_WORLD_SOURCE)
+        .arg(TEST_HOW_ARE_YOU_SOURCE)
+        .arg("-i")
+        .fails()
+        .no_stdout();
+}
+
 #[test]
 fn test_cp_arg_interactive() {
     let (at, mut ucmd) = at_and_ucmd!();
@@ -241,11 +251,24 @@ fn test_cp_arg_interactive() {
     at.touch("b");
     ucmd.args(&["-i", "a", "b"])
         .pipe_in("N\n")
-        .succeeds()
+        .fails()
         .no_stdout()
         .stderr_is("cp: overwrite 'b'? ");
 }
 
+#[test]
+fn test_cp_arg_interactive_update() {
+    // -u -i won't show the prompt to validate the override or not
+    // Therefore, the error code will be 0
+    let (at, mut ucmd) = at_and_ucmd!();
+    at.touch("a");
+    at.touch("b");
+    ucmd.args(&["-i", "-u", "a", "b"])
+        .pipe_in("N\n")
+        .succeeds()
+        .no_stdout();
+}
+
 #[test]
 #[cfg(target_os = "linux")]
 fn test_cp_arg_link() {